I've always loved the sheer size and straight on shot of a peripheral ported intake, but there's a problem. With a peripheral intake and a peripheral exhaust you encounter massive overlap that necessitates a 2000+rpm idle and no power until 9,000 to 10,000 rpm, not very practical for the street. Why not create an engine that is similar to a stock NA 13B but with the porting configuration reversed? You're going to get all the overlap reducing benefits of a regular engine but with the flow importance placed where it always should have been: the intake.

Mazda, for who knows what reason, decided that the straight open port should be devoted to evacuating the exhaust and that the intake air should have to flow though a smaller bent port, that causes the air to make a 90 degree turn, to get into the chamber. This is the opposite of what the V8 guys do: placing emphasis on a larger intake valve so as to get more air and fuel into the chamber. I think it's worth accepting a less than ideal amount of exhaust flow if it means the intake will realize a much greater cross sectional port diameter and perfectly straight shot into the engine.

With the debut of the Renesis engine we would actually have a platform that would allow a side exhaust port with a peripheral intake...with a little work. Devcon fill the intake and have R.B. peripheral port your Renesis housings, just like they would on a regular engine, only this time your exhaust will be in the side housings. It would be interesting to see just how well the engine does with the smaller restrictive port put where it finally belongs: on the exhaust side.

What do you guys think?

 

I dont know why you are bothering posting this in this section......

 

Let's just say I'm a lounge guy.

 

I thought of that idea a while back. Until someone actually tries it who knows how well it would work. Who cares where this post is located? I sure don't.

Fred

 

that is a very interesting idea... but you do have to give mazda engineers a little credit. im sure when designing the renesis they ran through every possible port position to make an engine that could have a usable power band and still make 250hp n/a.

 

In some of the Japanese tuner mags I have seen "sequential ported" motors, where the side ports on the ends of the motor are filled up, and the runners sent to a new peripheral intake port instead. I assume some sort of valve regulates the flow so you can pick high flow or good idle. Or maybe they just run it completely open and have crap idle, I can't read enough Japanese to tell from the text that came with it.

 

That's funny, I was thinking about this while grinding metal for 10.5 hrs at work today...

I think that with side exhaust ports and periperial intake ports, it would be harder to create a high HP set up. It may make a nice street driving everyday car though. I think the exhaust ports would be too small and cramped to flow big HP numbers unless you gave them a bridgeport, which may not be too good subjecting a 3.5mm bridge of metal to 1700 degree EGT's hmmm..
Periperial intake ports may also initiate symptoms such as a poor idle, and hard to tune the correct air/fuel mixture over the entire RPM range. Kind of similar to when owners switch their 4-cyls to individual short ram throttle boddies. Makes good power though

I think the ideal street rotory would be ported like the Renesis (both side). That should give you a huge wide powerband and good torque curve. (much like the RX-8, which you have 85% of your torque available by 2500? rpm and it peaks at 7500rpm.

The ideal NA rotary for power would be periperial intake and exhaust ports, which is already tested and proven in a way, with a nice super high compression ratio.

Just some thoughts I had while working today. Tell me if you think they are valid of if I was getting metal shavings from the griding into my sences.

 

Yes, it could be superior. The port overlap period would be shifted to BTDC which is a good thing for low-end power.

 

Well, when you think about any type of performance peripheral setup you're goin to run into a lot of overlap, which ruins streetability. I think Mazda actually did hit the nail on the head with the new Renesis because cross-sectional side-port area has been increased to about the size of your average bridgeport but with ZERO overlap! Another sweet thing is that all the technology of Dynamic Effect Intake and 6 port technology is being carried over to this "bridgeport like" motor. It's a little like keeping your cake and eating it too, but I'm sure it gets better. With the obvious fact of zero overlap doesn't that leave room for still greater enlargement of the ports? Hopefully Mazda left a little extra metal around the ports to be ported and polished away...only time will tell.

Anyone got an idea of how much the Renesis will make with exhaust, intake, and chip? I'm hoping for around 300hp when I get around to makin a fast Rx-3 all motor drag car...maybe with a 75 shot a NAWZZZ.

Oh, and if Mazda is readin this ****: better get that rotary crate engine program goin! WE WANT RENNIES!

 

Here's my take.

The amount of overlap in a side-intake peripheral-exhaust is not a problem, after all it's The Way Mazda Did Things since the 60's. Why should a peripheral-intake side-exhaust be any different?

 

Have you ever been in a car with a PP in it? the ones i have been in have pulled like stink once they hit arond 5500 - similar to a Wewy BIg Turbo

 

There are a couple of Puerto Ricans (crazy guys down there!) running a combination of side and small peripheral intake ports. Jaytech used to sell the manifold. They had no low end power but those guys don't care. Their peripherals were fairly small anyways. You don't want them to be too big while still using side ports since intake velocity would be poor everywhere. The thing to do would be to use a 4 barrel vacuum secondary Holley carb. Use 2 side intake ports (preferably the outer ones) and 2 fairly small peripheral ports. Set the vacuum secondaries to open around 4k or so and go for it. It should work and still idle and make decent power down low. Someone needs to build one. Sounds good to me.

 

I would like to see someone build a motor with stock side intake ports that are used at low rpm, untill about the time the secondary injectors come online. Then you open up a throttle plate that operates a set of periphial ports.

It'll take a special manifold and vacuum or electronicly controlled secondaries similar to whats is already on the stock manifold.

 

Guys have been doing this. The only thing you gain is a better idle and thats about it. a pp pulls very close to the same streangth as a side intake port motor does in the low end, and as was already corrected once, p ports pull hard starting at 5k and thats about where regular port motors start to realy optimize also.

CJG

 

The problem here is the overlap is still here.

you'd need shutters that are molded into the housings where the intake p.port and exhaust p. ports are. This would near eliminate low end port overlap. close them at low rpms, then when the two torque curves cross, open up the p.ports (probably above 4k) It'd be easiest to use two electric motors governed by an RPM switch.

this would keep the driveability of the stock ports emissions of the renesis at cruising RPM. then when u open her up for a few secs, TAKE OFF to the great white north.

I wish i could work for mazda.

I think mazda should make seals and housings an arc, they'd be more resistant to flexing at high RPMs.

 

If you do manage to make the engine breathe/behave correctly across a range that extends from idle to past 10,000 RPM, then what do you do to keep the mechanical stresses under control at the top end of that range where you're making your crazy power?

What are the factors/issues involved?

This is really interesting.
Phil.

 

Add a centre bearing, and up the oil pressure - nothing else is REALLY needed.

This is how I'm hoping to setup mine when i get a garage (sometime next year)

# a HIF44 on the primaries (throttle controlled)
# a HIF38 for each of the secondaries (vacuum controlled)
# a HIF 38 for each of the PPs (vacuum controled)

The secondaries and PPs would have a valve to their vacuum sources, so I have the choice of having either:

# economy mode (primaries only),
#"normal" mode (primaries and secondaries)
# or POWER (all ports)

The diaphragm I've got so far is from the standard Nikki carb. Does anyone know what RPM that starts to open at?

I can easily make the inlets and cabling, but I'm not sure on which diaphragm would be the best for the PPs

 

Chairchild - this sounds like a really interesting setup. I'm looking forward to hearing about your results!

Take it easy,
Phil.

 

The best bit is, it's going in a beetle

 

what if you did this on a new RENESIS motor, with that special seal that kills all the overlap? Wouldnt that extingush all worries about shitty idle on a PP?

-Zach

 

rob@pineapple already has several different designs using this and other (more ingenious) principles that are working he showed me when i was up there

he's intrigued by the new RX8 port timing/shapes/overlaps/layouts

stay tuned for some interesting developments from him

 

Anything ever come of this?

 

one of the airplane guys did it with ok results.

since the Rx8's are about to turn 10, we have some real world experience with the side port engines, and its mixed. the side exhaust ports turn out to be the limiting factor in those engines, as they are small, and there is no room to port. also the side and corner seals are in the exhaust stream, and they don't last as long

the intake ports and manifolds are really nice though, so the "hot" setup in Japan is to block off the side ports and run normal GSL-SE rotor housings.